Chinese Physics Letters
The magnetic properties of 1 T-TaS2 and 1 T-Fe-0.07 Ta-0.93 S-2 have been studied, Experimental results show that the phase transition temperature of 1 T-TaS2 is a function of the magnetic field, At low temperatures, both compounds are in a mixed state of charge density wave -spin density wave due to the coherent superposition of antiferromagnetic coupling.
关键词:
density
Xiujian Chou
材料科学技术（英文）
Ba1-xSrxTiO3 ceramics, doped with B2O3-Li2O glasses have been fabricated via a traditional ceramic process at a low sintering temperature of 900 °C using liquid-phase sintering aids. The microstructures and dielectric properties of B2O3-Li2O glasses doped Ba1-xSrxTiO3 ceramics have been investigated systematically. The temperature dependence dielectric constant and loss reveals that B2O3-Li2O glasses doped Ba1-xSrxTiO3 ceramics have diffusion phase transformation characteristics. For 5 wt% B2O3-Li2O glasses doped Ba0:55Sr0:45TiO3 composites, the tunability is 15.4% under a dcpplied electric field of 30 kV/cm at 10 kHz; the dielectric loss can be controlled about 0.0025; and the Q value is 286. These composite ceramics sintered at low temperature with suitable dielectric constant, low dielectric loss, relatively high tunability and high Q value are promising candidates for multilayer low-temperature co-fired ceramics (LTCC) and potential microwave tunable devices applications.
关键词:
Sintering
卫英慧
,
贾连锁
,
胡兰青
,
许并社
稀有金属材料与工程
T1(Al2CuLi)相是Al-Li-Cu-Zr合金中的重要强化相.通过TEM在对T1相结构和形貌分析的基础上,构造了T1相的结构.T1相晶核以ABCBA的堆垛顺序,共由36个原子组成,其晶格常数a=0.495nm,c=0.933nm.与基体的位相关系为:{0001}T1∥{111}α,<>T1∥<110>α.合金中铜原子的偏聚降低了基体的层错能,从而为T1相依赖扩散层错形核提供了有利条件.T1相长大依赖于原子扩散和台阶滑移,是一种长程扩散控制的台阶机制.
关键词:
Al-Li基合金
,
相变
,
时效
,
T1相
Physical Review B
The magnetic properties and phase transitions of 1T-TaS2 and 1T-Fe0.07Ta0.93S2 have been studied in the interval of 1.5-300 K and over the range of 100 Oe-60 kOe. Experimental results show that at high temperatures the compounds are in a diamagnetic state and the commensurate-charge-density-wave-triclinic-nearly-commensurate transition temperature of 1T-TaS2 decreases with increasing magnetic field. The amount of variation is a function of the magnetic field. At low temperatures both 1T-TaS2 and 1T-Fe0.07Ta0.93S2 are in a paramagnetic state owing to the localized moments that come from the single Anderson-Mott localization state. The curves of magnetization versus temperature do not follow the Curie law or Curie-Weiss law, but can be described fairly well as M = M(0) + gamma T--n. The fitting parameters of experimental curves show that a part of the neighboring moment appears as antiferromagnetic coupling due to exchange interaction between the moments. The magnetic-field dependence of magnetization exhibits a complicated feature at low temperature. It shows that the compounds may undergo a phase transition at the maximum value of magnetization and then they are probably in a mixed charge-density-wave-spin-density-wave (CDW-SDW) state or SDW state due to the coherent superposition of the antiferromagnetic coupling.
关键词:
metal-insulator-transition;density-wave domains;high magnetic-fields;charge-density;doped 1t-tas2;coexistence;microscopy;systems;silicon;2h-tas2
贾玉鑫
,
黄金亮
,
冯剑
材料热处理学报
采用Gleeble-1500D热模拟机对Mg-8Li-2Al-1Zn合金进行热压缩实验,研究了变形温度为523 ～ 723 K、应变速率为0.01 ～10 s-1条件下的合金热变形行为,并建立了合金的流变应力本构方程及热加工图.结果表明:Mg-8Li-2Al-1Zn合金的流变曲线均属于动态再结晶型,流变应力随着温度升高(应变速率降低)而减小.显微组织的变化验证了动态回复和动态再结晶的发生.Mg-8Li-2Al-1Zn合金流变应力本构关系可以用双曲正弦函数和Z参数准确的描述,平均应力指数为4.62,平均热激活能为139.35 J/mol.根据建立的加工图,预测合金热变形的最佳工艺参数为:523 ～573 K,0.1～1 s-1.
关键词:
镁锂合金
,
热变形
,
动态再结晶
,
本构方程
,
微观组织
钟耀东
,
李志同
,
郭远刚
,
周权
,
周凤瑞
,
强颖怀
,
杨凌玲
,
霍瑛
,
赵思茜
材料科学与工程学报
富锂锰过渡金属层状正极材料以其成本低、安全、容量高受到广泛关注,X射线衍射（XRD）和电化学性能测试显示以共沉淀结合煅烧成功合成富锂层状正极材料zLi2MnO3.（1-z）LiMn0.4Ni0.4Co0.2O2（z=0.2,0.4,0.6）。其中z=0.4组分的放电容量达到210mAh/g（2-4.8V,0.05C）,远高于z=0.6组分,而经20个充放电循环的稳定性也优于z=0.2组分。微分容量分析表明z=0.2组分中因Ni/（Co＋Mn）比值较大和Li2MnO3含量较少可能导致其容量逐渐衰减。z=0.6则因所含LiMn0.4Ni0.4Co0.2O2量较少,造成其放电容量较低;z=0.4拥有最佳Li2MnO3及LiMn0.4Ni0.4Co0.2O2组合使其容量和循环性能最好。
关键词:
zLi2MnO3·(1-z)LiMn0.4Ni0.4Co0.2O2
,
正极材料
,
循环性能
,
容量
冷荣军
,
蒋成颖
,
孙彬
,
杨宏顺
低温物理学报
本文报道了自助溶剂法制备的Li1-xNaxCu2O2（x=0,0.05,0.1,0.2）单晶沿c方向的磁化率随温度变化χ（T）的实验结果.随着Na掺杂量的增加,磁化率整体上移,高温区磁化率更加平缓;不同掺杂样品磁化率都在40K附近存在最大值,掺杂没有引起磁化率最大值对应的温度的变化,但引起了更低温下（T〈14K）磁化率的上翘,表明掺杂引入的无序使得自旋能隙被重新填充.高温区磁化率（T〉60K）拟合结果得到的铁磁相互作用J1、反铁磁相互作用J2均随掺杂量增加同步减小,阻挫变量α保持不变.X射线衍射结果表明Na均匀的的掺杂在母体中,晶胞参数a、b、c均随着掺杂量的增加而增大.磁相互作用的减小是与晶胞参数a、b、c的增加相关的.阻挫变量α的不变与磁化率最大值对应的温度以及体系最大概率磁转变温度的不变对应,从实验上证明了阻挫变量α是决定受挫体系性质的主要因素.
关键词:
准一维磁性材料
,
含阻挫的自旋体系
,
自旋能隙
Journal of Alloys and Compounds
The formation of impurity Li(x)Ni(1-x)O when synthesizing spinel LiNi(0.5)Mn(1.5)O(4) using solid state reaction method, and its influence on the electrochemical properties of product LiNi(0.5)Mn(1.5)O(4) were studied. The secondary phase LixNi(1-x)O emerges at high temperature due to oxygen deficiency for LiNi(0.5)Mn(1.5)O(4) and partial reduction of Mn(4+) to Mn(3+) in LiNi(0.5)Mn(1.5)O(4). Annealing process can diminish oxygen deficiency and inhibit impurity Li(x)Ni(1-x)O. The impurity reduces the specific capacity of product, but it does not have obvious negative effect on cycle performance of product. The capacity of LiNi(0.5)Mn(1.5)O(4) that contains Li(x)Ni(1-x)O can deliver about 120 mAhg(-1). (C) 2011 Elsevier B.V. All rights reserved.
关键词:
Lithium ion batteries;LiNi(0.5)Mn(1.5)O(4);Impurity Li(x)Ni(1-x)O;Electrochemical properties;lithium batteries;rate capability;spinel;performance
王金龙
,
崔大伟
材料热处理学报
采用碳酸盐共沉淀法合成了Li1＋xNi1/3Co1/3Mn1/3O2正极材料。用X射线粉末衍射仪、高频电感耦合等离子体原子发射光谱仪和扫描电子显微镜对材料的晶体结构、化学元素组成和表面形貌进行了分析研究。将正极材料Li1＋xNi1/3Co1/3Mn1/3O2制成电极极片,组装成混合动力车用3Ah高功率电池进行测试。分析测试结果表明,合成的正极材料Li1＋xNi1/3Co1/3Mn1/3O2具有典型的α-NaFeO2结构,粒径约为10μm。在室温（25℃）,电池经2000次充放电循环后容量可保持80%;在50%DOD下,电池10 s脉冲输出功率密度为2100 W/kg,输入功率密度为2700 W/kg。
关键词:
正极材料
,
高功率
,
锂离子电池
,
混合动力车
